The well known electrophotographic reproduction process, as practiced in a copier or a printer, involves the toning of an electrostatic latent image with toner powder. This toner image is then transferred to a substrate medium, for example, paper in sheet or fanfold form. This substrate's toner image must now be fused or fixed to the substrate surface in order to form a permanent image thereon.
A well known fuser construction and arrangement provides two circular cylinder rolls, for example, about 3 inches in diameter and about 16 inches in axial length. These rolls are in pressure contact, and form an elongated fusing nip through which the sheet passes. Prior art devices of this type have used rolls that are unheated (i.e., cold roll pressure fusing), as well as one or both of the rolls heated (i.e., hot roll pressure fusing).
These two rolls are preferably covered with a material which is abherent to the toner being fused.
In addition, one or both of the rolls may be covered with an elastomer, and a silicone release oil may be applied to the elastomer surface by the use of a wick or the like.
While present day roll fusers are for the most part reliable devices, the possibility of a sheet of paper jamming as it is passing through the fuser has not been completely eliminated, and means must be provided to allow manual jam clearance to occur in a convenient, safe and simple manner.
This problem has been addressed in the art, and U.S. Pat. Nos. 4,421,401; 4,428,660; 4,475,804; 4,498,757; 4,531,823 and 4,589,758 are exemplary of prior arrangements.
A more highly developed fuser jam clearance mechanism is shown in U.S. Pat. No. 4,110,068. In this patent, a manually operable handle is provided so that the operator can open the fuser, exposing the fuser's sheet path, thus allowing a jammed sheet to be removed.
The present invention is an improvement upon these prior devices, in that fewer parts (i.e., lower cost) are required to provide reliable operation.